This application claims priority of European Application No. 01303395.6 filed on Apr. 11, 2001.
The present invention relates generally to a base station in a communication network and particularly to a divider circuitry in the receiving path of a radio communication apparatus which comprises divider units and respective receiver circuits.
In global systems for mobile communication, base stations are provided having one or a plurality of antennas which receive radio signals on a channel and amplify same to supply the signal to divider units and the receiving circuitry of the base station. To that purpose, the received and preamplified signal has to be split up by the divider units n sub-channels onto a plurality of outputs. The number of the divider units and the outputs thereof is oriented on the maximum number of transmitter-receiver-units (transceiver units) of a base station which has to service its cell. There are different configurations of cells, for example omnidirectional cells and sectoral cells, and also the grouping of the transceivers within a base station may be different among base stations. Mostly, the divider units are positioned so as the connections to the transceivers are short and simple.
Base stations usually comprise a main receiver branch and a so-called diversity receiver branch. The above-described scheme of signal splitting is commonly used for both branches. The divider units multiply the signal into several paths so that one input is connected to a plurality of outputs. This is made by the help of passive or active divider circuits, for example transformers, or by using divider circuits in cascades. Each step of division means a division in power or attenuation in the signal paths corresponding to the number of outputs.
A base station may comprise 12 transceivers for servicing the cell to which it is assigned wherein the cell may comprise for example three sectors. This means four transceivers and four divider units per receiving path. If there is diversity, eight divider units are necessary for servicing the main and the diversity branch. Often, a network owner or carrier wishes to use a cell configuration having six transceivers per sector. This means that two of the divider units have outputs which are not used and mean costs for a hardware and space in the base station without having utility thereof.
It is an object of the present invention to reduce the hardware costs in base stations wherein the number of transceivers is different to 2n(n=2, 3, 4). In such cases, the costs for the divider units and the necessary space for these divider units is to be reduced.
In a preferred embodiment, a special switchable, divider unit is provided which comprises two signal inputs and three divider elements. Each divider element has an input and a pair of outputs. Switching means may take a first and a second positions. In the first position, the first signal input is divided into four output signals along the divider elements which are connected in cascade. In the second position of the switching means, the first divider in the cascade is bypassed, that is, the first signal input is connected to the input of the second divider element, and the second signal input is connected to the input of the third divider element. By doing so, one signal input can be assigned to four signal outputs, or two signal inputs can be assigned to each a pair of outputs.
It may be desirable to have the same alternation characteristic for every output in the first and the second positions of the switching means. To that end, when bypassing the first divider element, each an attenuating member is inserted between signal input and input of the second and the third divider elements, respectively. The attenuating member should have the same characteristic as the first divider element which it bypasses. By these means, the alternation characteristic in the receiving path is the same for all variations of configuration.
The divider units can be arranged directly adjacent to transmitting devices or transceivers so that the length of connecting cables between the divider units and the transceivers can be kept low and can have a simple structure.